U.S. patent application number 16/406098 was filed with the patent office on 2020-11-12 for methods of area-selective atomic layer deposition.
The applicant listed for this patent is International Business Machines Corporation. Invention is credited to Noel Arellano, Ekmini A. De Silva, Gregory M. Wallraff, Rudy J. Wojtecki.
Application Number | 20200354834 16/406098 |
Document ID | / |
Family ID | 1000004110839 |
Filed Date | 2020-11-12 |
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United States Patent
Application |
20200354834 |
Kind Code |
A1 |
De Silva; Ekmini A. ; et
al. |
November 12, 2020 |
METHODS OF AREA-SELECTIVE ATOMIC LAYER DEPOSITION
Abstract
A method is described for selectively forming alumina film
layers on a silicon oxide surface by atomic layer deposition (ALD)
in the presence of a metal-containing surface when each surface is
exposed to the ALD reactants (i.e., a blocking layer is not used to
prevent ALD reactants from contacting the metal-containing layer).
Also described are methods of determining conditions for
area-selective atomic layer deposition (AS-ALD) on a substrate
containing two or more different surface materials using a database
of ALD reactions.
Inventors: |
De Silva; Ekmini A.;
(Slingerlands, NY) ; Arellano; Noel; (Freemont,
CA) ; Wallraff; Gregory M.; (San Jose, CA) ;
Wojtecki; Rudy J.; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
International Business Machines Corporation |
Armonk |
NY |
US |
|
|
Family ID: |
1000004110839 |
Appl. No.: |
16/406098 |
Filed: |
May 8, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 16/403 20130101;
C23C 16/04 20130101; H01L 21/02178 20130101; C23C 16/45553
20130101; C23C 16/45527 20130101; H01L 21/0228 20130101; C23C
16/45544 20130101 |
International
Class: |
C23C 16/455 20060101
C23C016/455; H01L 21/02 20060101 H01L021/02; C23C 16/04 20060101
C23C016/04; C23C 16/40 20060101 C23C016/40 |
Claims
1. A method, comprising: providing a substrate comprising a silicon
dioxide surface and a zero valent metal- containing surface; and
forming a layered structure comprising a layer of alumina
selectively disposed on the silicon dioxide surface relative to the
metal-containing surface using an atomic layer deposition (ALD)
process, the process comprising one or more cycles of i) contacting
the silicon dioxide surface and the metal-containing surface of the
substrate with an organoaluminum compound at a temperature between
0.degree. C. and 100.degree. C., thereby forming a treated
substrate and ii) contacting the treated substrate with water,
thereby forming the layered structure.
2. The method of claim 1, wherein said contacting the silicon oxide
surface and the metal-containing surface with an organoaluminum
precursor is for a period of 1-10 minutes.
3. The method of claim 1, wherein said contacting the treated
substrate with water is for a period of 1-10 minutes.
4. The method of claim 1, wherein the organoaluminum precursor is
trimethylaluminum.
5. The method of claim 1, wherein said contacting the silicon oxide
surface and the metal-containing surface with an organoaluminum
precursor is performed at a temperature between 60.degree. C. and
90.degree. C.
6. The method of claim 1, wherein the method further comprises
treating the layered structure with a reducing agent.
7. The method of claim 1, wherein the method comprises annealing
the layered structure at a temperature above 100.degree. C.
8. The method of claim 1, wherein the metal-containing surface
comprises a zero-valent metal selected from the group consisting of
copper, chromium, and cobalt.
9. The method of claim 1, wherein the metal-containing surface
comprises zero-valent copper.
10. A method, comprising: providing a database of performed atomic
layer deposition (ALD) reactions, the ALD reactions including
successes and failures depositing target compositions on different
substrate surfaces; selecting a target composition to be formed by
ALD; selecting a target material on which to selectively deposit
the target composition by ALD; selecting a non-target material on
which deposition by ALD of the target composition is not desired;
determining from the database i) common ALD conditions for ALD
reactions that form the target composition on the target material
and ii) ALD reactions that do not form the target composition on
the non-target material; and depositing the target composition by
ALD on a substrate using the common ALD conditions, the substrate
comprising i) target surface regions containing the target material
and ii) non-target surface regions containing the non-target
material, thereby forming a modified substrate comprising the
target composition substantially or wholly disposed on the target
surface regions.
11. The method of claim 10, wherein the target composition is
alumina.
12. The method of claim 11, wherein the target material is silicon
oxide.
13. The method of claim 12, wherein the non-target material is a
zero-valent metal selected from the group consisting of copper,
chromium, and cobalt.
14. The method of claim 13, wherein the ALD conditions include
performing the ALD at a temperature between 0.degree. C. and
100.degree. C.
15. The method of claim 10, wherein the ALD conditions exclude a
blocking layer on the non-target material during the ALD.
16. The method of claim 10, wherein the non-target material
contacts each reactant used to form the target composition during
said depositing.
17. A computer program product, comprising a computer readable
hardware storage device having a computer-readable program code
stored therein, said program code configured to be executed by a
processor of a computer system to implement a method comprising:
providing a database of performed atomic layer deposition (ALD)
reactions, the ALD reactions including successes and failures
depositing target compositions on different substrate surfaces;
selecting a target composition to be formed by ALD; selecting a
target material on which to selectively deposit the target
composition by ALD; selecting a non-target material on which
deposition by ALD of the target composition is not desired;
determining from the database common ALD conditions for ALD
reactions that form the target composition on the target material
and ALD reactions that do not form the target composition on the
non-target material; and depositing the target composition by ALD
on a substrate comprising target surface regions containing the
target material and the non-target surface regions containing
non-target material using the common ALD conditions, thereby
forming a modified substrate comprising the target composition
substantially or wholly disposed on the target surface regions.
18. A system comprising one or more computer processor circuits
configured and arranged to: provide a database of performed atomic
layer deposition (ALD) reactions, the ALD reactions including
successes and failures depositing target compositions on different
substrate surfaces; select a target composition to be formed by
ALD; select a target material on which to selectively deposit the
target composition by ALD; select a non-target material on which
deposition by ALD of the target composition is not desired;
determine from the database common ALD conditions for ALD reactions
that form the target composition on the target material and ALD
reactions that do not form the target composition on the non-target
material; and deposit the target composition by ALD on a substrate
comprising target surface regions containing the target material
and the non-target surface regions containing non-target material
using the common ALD conditions, thereby forming a modified
substrate comprising the target composition substantially or wholly
disposed on the target surface regions.
19. A method, comprising: providing a substrate that includes (i) a
first portion made of zero-valent copper and (ii) a second portion
made of silicon oxide having -OH groups attached thereto;
contacting the first portion and the second portion with a compound
that includes aluminum (Al) for a predetermined first period of
time at a temperature less than 100.degree. C., thereby forming a
treated substrate comprising a layer of aluminum-containing
material substantially or wholly disposed on, and bound to, the
second portion of the substrate, the compound being substantially
non-reactive with the copper during the first period; removing any
of the compound that is not bound to the treated substrate;
introducing water to the treated substrate for a predetermined
second period, thereby forming an Al.sub.2O.sub.3 layer
substantially or wholly disposed on the second portion; and
repeating the steps of contacting, removing, and introducing a
given number of times, thereby forming additional layers of
Al.sub.2O.sub.3 over the second portion of the substrate, wherein
said given number is selected to avoid build-up of Al-containing
compounds on the first portion of the substrate.
20. The method of claim 19, wherein the method is carried out at a
temperature between 60.degree. C. and 90.degree. C.
21. The method of claim 19, further comprising densifying the
additional layers through an annealing process.
22. The method of claim 19, wherein the method comprises contacting
the water-treated substrate with a reducing agent, thereby reducing
any oxidized copper of the first portion to a zero-valent
copper.
23. The method of claim 22, wherein said contacting the water
treated substrate with a reducing agent increases etch resistance
of the Al.sub.2O.sub.3 layer.
24. A layered structure formed by the method of claim 19, the
layered structure comprising a substrate having a surface
comprising (i) a first portion made of zero-valent copper and (ii)
a second portion comprising one or more layers of Al.sub.2O.sub.3
disposed on silicon oxide.
25. The layered structure of claim 24, wherein the layered
structure is a sacrificial etch mask in a lithography process.
26. The layered structure of claim 24, wherein the layered
structure is a material component in a semiconductor device.
Description
BACKGROUND
[0001] The present invention relates to methods of area-selective
atomic layer deposition (AS-ALD), more specifically to the AS-ALD
of alumina (Al.sub.2O.sub.3) on silicon oxide (SiO.sub.2).
[0002] As the miniaturization of semiconductor technology
continues, the need for deposition techniques that offer atomic
level resolution has become increasingly important.
[0003] Chemical vapor deposition (CVD) is a chemical process
designed to produce high-performance solid materials used in
semiconductor processing. Typically, CVD techniques expose a
substrate to one or more volatile precursors that decompose and/or
react on the surface of the substrate to produce the deposited
material. By-products may be produced and, subsequently, removed
via gas flow through the reaction chamber. As non-limiting
examples, CVD may be used to deposit layers of polysilicon,
SiO.sub.2, Si.sub.3N.sub.4, SiNH, HfO.sub.2, Mo, Ta, Ti, TiN and
W.
[0004] Atomic layer deposition (ALD) is another thin film
deposition technique. ALD involves the use of precursors
(chemicals) that react with the surface separately in a sequential
manner. A thin film is grown by repeatedly exposing the precursors
to the substrate. While similar in chemistry to CVD, ALD breaks the
film-forming process into two or more sequential reactions,
delivering the precursors of the ALD-formed material in separate
steps to the substrate. ALD enables atomic scale deposition control
and can achieve growth on the order of one monolayer or less per
cycle. Separation of the precursors may be obtained by utilizing a
purge gas (e.g., N.sub.2, Ar) after each precursor to remove excess
precursor from the process chamber and reduce or prevent parasitic
CVD processes (e.g., extra deposition on the substrate via CVD).
Fundamentally, this technique takes advantage of substrate surface
groups that bind with organometallic precursors, thereby forming
bound forms of the organometallic materials. In a separate step the
bound organometallic materials are treated with water, ozone,
and/or oxygen, thereby forming metal oxide bound to the substrate
surface. As non-limiting examples, ALD may be used to deposit
layers of Al.sub.2O.sub.3, TiO.sub.2, SnO.sub.2, ZnO, HfO.sub.2,
TiN, TaN, WN, NbN, Ru, Ir, Pt and ZnS.
[0005] Increasingly important are area-selective ALD processes
(AS-ALD), which deposit film-forming precursors substantially or
wholly in a desired pattern or location of the substrate. By
controlling the area where these metals/metal oxides are deposited,
the number of lithography, processing and etching steps can be
reduced, thereby making this process highly sought by semiconductor
manufacturers.
[0006] Conventional lithographic materials (such as patternable
polymers) have been used to block (inhibit) surface reaction sites
in ALD processes. Even thinner blocking layers have been
demonstrated using self-assembled monolayers (SAMs) that show high
levels of selectivity. However, these methods are disadvantaged by
requiring additional processing steps associated with patterning
and removing the blocking layer, and additionally long deposition
times.
[0007] A specific need exists for depositing alumina
(Al.sub.2O.sub.3) more efficiently on silicon oxide (SiO.sub.2)
surfaces in the presence of copper metal surfaces without utilizing
blocking layers.
SUMMARY
[0008] Accordingly, a method is disclosed, comprising:
[0009] providing a substrate comprising a silicon dioxide surface
and a zero valent metal-containing surface; and
[0010] forming a layered structure comprising a layer of alumina
selectively disposed on the silicon dioxide surface relative to the
metal-containing surface using an atomic layer deposition (ALD)
process, the process comprising one or more cycles of i) contacting
the silicon dioxide surface and the metal-containing surface of the
substrate with an organoaluminum compound at a temperature between
0.degree. C. and 100.degree. C., thereby forming a treated
substrate and ii) contacting the treated substrate with water,
thereby forming the layered structure.
[0011] Another method is disclosed, comprising:
[0012] providing a database of performed atomic layer deposition
(ALD) reactions, the ALD reactions including successes and failures
depositing target compositions on different substrate surfaces;
[0013] selecting a target composition to be formed by ALD;
[0014] selecting a target material on which to selectively deposit
the target composition by ALD;
[0015] selecting a non-target material on which deposition by ALD
of the target composition is not desired;
[0016] determining from the database i) common ALD conditions for
ALD reactions that form the target composition on the target
material and ii) ALD reactions that do not form the target
composition on the non-target material; and
[0017] depositing the target composition by ALD on a substrate
using the common ALD conditions, the substrate comprising i) target
surface regions containing the target material and ii) non-target
surface regions containing the non-target material, thereby forming
a modified substrate comprising the target composition
substantially or wholly disposed on the target surface regions.
[0018] Also disclosed is computer program product, comprising a
computer readable hardware storage device having a
computer-readable program code stored therein, said program code
configured to be executed by a processor of a computer system to
implement a method comprising:
[0019] providing a database of performed atomic layer deposition
(ALD) reactions, the ALD reactions including successes and failures
depositing target compositions on different substrate surfaces;
[0020] selecting a target composition to be formed by ALD;
[0021] selecting a target material on which to selectively deposit
the target composition by ALD;
[0022] selecting a non-target material on which deposition by ALD
of the target composition is not desired;
[0023] determining from the database common ALD conditions for ALD
reactions that form the target composition on the target material
and ALD reactions that do not form the target composition on the
non-target material; and
[0024] depositing the target composition by ALD on a substrate
comprising target surface regions containing the target material
and the non-target surface regions containing non-target material
using the common ALD conditions, thereby forming a modified
substrate comprising the target composition substantially or wholly
disposed on the target surface regions.
[0025] Further disclosed is a system comprising one or more
computer processor circuits configured and arranged to:
[0026] provide a database of performed atomic layer deposition
(ALD) reactions, the ALD reactions including successes and failures
depositing target compositions on different substrate surfaces;
[0027] select a target composition to be formed by ALD;
[0028] select a target material on which to selectively deposit the
target composition by ALD;
[0029] select a non-target material on which deposition by ALD of
the target composition is not desired;
[0030] determine from the database common ALD conditions for ALD
reactions that form the target composition on the target material
and ALD reactions that do not form the target composition on the
non-target material; and
[0031] deposit the target composition by ALD on a substrate
comprising target surface regions containing the target material
and the non-target surface regions containing non-target material
using the common ALD conditions, thereby forming a modified
substrate comprising the target composition substantially or wholly
disposed on the target surface regions.
[0032] Also disclosed is a method, comprising:
[0033] providing a substrate that includes (i) a first portion made
of zero-valent copper and (ii) a second portion made of silicon
oxide having -OH groups attached thereto;
[0034] contacting the first portion and the second portion with a
compound that includes aluminum (Al) for a predetermined first
period of time at a temperature less than 100.degree. C., thereby
forming a treated substrate comprising a layer of
aluminum-containing material substantially or wholly disposed on,
and bound to, the second portion of the substrate, the compound
being substantially non-reactive with the copper during the first
period;
[0035] removing any of the compound that is not bound to the
treated substrate;
[0036] introducing water to the treated substrate for a
predetermined second period, thereby forming an Al.sub.2O.sub.3
layer substantially or wholly disposed on the second portion; and
repeating the steps of contacting, removing, and introducing a
given number of times, thereby forming additional layers of
Al.sub.2O.sub.3 over the second portion of the substrate, wherein
said given number is selected to avoid build-up of Al-containing
compounds on the first portion of the substrate.
[0037] The above-described and other features and advantages of the
present invention will be appreciated and understood by those
skilled in the art from the following detailed description,
drawings, and appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0038] FIG. 1 is a schematic of the disclosed process of
area-selective deposition of aluminum oxide on a silicon dioxide
surface, which takes advantage of the native reactivity difference
of Cu surfaces at low temperature ALD cycles.
[0039] FIG. 2 is a flow diagram of a method of choosing conditions
for area-selective ALD that utilizes a database of performed ALD
reactions.
[0040] FIG. 3 is a block diagram showing a structure of a computer
system and computer program code that may be used to implement a
method of processing, including natural-language processing, to
implement a method of area-selective ALD.
[0041] FIG. 4 is a graph showing XPS data of the Cu surface of
Example 1 at different number of ALD cycles. Example 1 samples have
SAMs on the Cu surface. Surface oxygen concentration of the copper
surface is constant up to 40 cycles, after which a continuous
increase is observed.
[0042] FIG. 5 is a graph showing XPS data of the SiO.sub.2 surface
of Example 1 at different numbers of ALD cycles.
[0043] FIG. 6 is a graph showing XPS data of the copper surface of
Example 2 at different numbers of ALD cycles. Samples of Example 2
have no SAM blocking layer on the Cu surface.
[0044] FIG. 7 is a graph showing XPS data of the chromium surface
of Example 3 at different numbers of ALD cycles. Samples of Example
2 have no SAM blocking layer on the copper surface.
[0045] FIG. 8 is a graph showing XPS data of the cobalt surface of
Example 4 at different numbers of ALD cycles. Samples of Example 4
have no SAM blocking layer on the cobalt surface.
DETAILED DESCRIPTION
[0046] Methods are disclosed for low temperature area-selective ALD
of an alumina film layer. The substrate for the disclosed methods
comprises two or more compositionally different surface regions. A
first region (first portion) of a substrate surface contains
silicon oxide. A second region (second portion) has a surface
containing a zero-valent metal, where the second portion can have
0% up to about 20% native oxide of the metal in contact with an
atmosphere. ALD deposition of a target composition is desired on
the first regions, designated target surfaces. No deposition is
desired on the second regions, designated non-target surfaces. The
disclosed methods deposit alumina selectively on the first regions
without using a blocking layer on the second regions to protect the
metal-containing surface during the ALD.
[0047] Also disclosed is a computer method for choosing materials
and conditions for selectively forming a film layer by ALD on a
target surface of a substrate without using blocking layer(s) on
non-target surface area(s) of the substrate. The ALD conditions are
chosen utilizing a database of ALD reactions and a computer program
for accessing the database. The computer program can also operate
the ALD apparatus using the selected materials and conditions. A
computer system for area-selective ALD film formation can comprise
the database of ALD reactions, computer program for accessing the
database, the ALD apparatus, a computer program operating the ALD
apparatus, and associated display, communications, network, and
electronic storage devices of the system.
[0048] An ALD cycle is typically conducted in a step-wise manner by
i) contacting a gaseous first reactant with the substrate, thereby
forming a first treated substrate, ii) purging excess first
reactant using an inert gas (e.g., argon, nitrogen), iii)
contacting a gaseous second reactant with the first treated
substrate, thereby forming a second treated substrate, and iv)
purging the excess second reactant, thereby forming a modified
substrate comprising a monolayer of the target composition disposed
on the target surface, the non-targeted surfaces being free of, or
substantially free of, the ALD-formed target composition. Herein,
an ALD cycle can comprise two or more sequential stages, each stage
involving a different reactant used to make a target
composition.
[0049] An ALD cycle can take from about 0.1 seconds to about 10
minutes to complete. Each ALD cycle deposits another monolayer of
the target composition on the previously deposited monolayer. The
change in thickness of the ALD-formed film layer per cycle is
referred to as the "growth per cycle" (GPC). The final thickness of
the ALD-formed layer is controlled by the number of ALD cycles
performed.
[0050] Herein, "silicon oxide" includes silicon dioxide (SiO.sub.2)
and tetravalent silicon species bonded to one or more hydroxyl
groups (i.e., --OH groups) such as, for example:
##STR00001##
[0051] Metal-containing surfaces can comprise zero valent and/or
ionic forms of metals including beryllium, magnesium, calcium,
strontium, barium, radium, aluminum, gallium, indium, thallium,
germanium, tin, lead, arsenic, antimony, bismuth, tellurium,
polonium, and metals of Groups 3 to 12 of the Periodic Table.
Metals of Groups 3 to 12 of the Periodic Table include scandium,
titanium, vanadium, chromium, manganese, iron, cobalt, nickel,
copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium,
ruthenium, rhodium, palladium, silver, cadmium, lanthanum, cerium,
praseodymium, neodymium, promethium, samarium, europium,
gadolinium, terbium, dysprosium, holmium, erbium, thulium,
ytterbium, lutetium, hafnium, tantalum, tungsten, rhenium, osmium,
iridium, platinum, gold, mercury, actinium, thorium, protactinium,
uranium, neptunium, plutonium, americium, curium, berkelium,
californium, einsteinium, fermium, mendelevium, nobelium,
lawrencium, rutherfordium, dubnium, seaborgium, bohrium, hassium,
meitnerium, darmstadtium, roentgenium, and copernicium. In an
embodiment, the metal-containing surface contains a metal selected
from the group consisting of copper, chromium, and cobalt.
[0052] The disclosed methods do not require a blocking layer on
non-target surface(s) to guide the adsorption of an ALD reactant to
a target surface area of the substrate. Herein, a blocking layer is
a temporary layer used on a non-target surface. The blocking layer
is removed from the ALD-modified substrate after an ALD process. In
an embodiment, the disclosed methods exclude the use of a blocking
layer.
[0053] The ALD process can include an optional treatment (e.g.,
reducing step) between ALD cycles or after completing all of the
ALD cycles that refreshes the surface properties of non-targeted
surfaces of the substrate. As a non-limiting example, the
non-target metal-containing surfaces can be treated with a reducing
agent (e.g., hydrogen delivered by the ALD apparatus) in order to
convert any oxidized metal of the non-targeted surfaces formed by
exposure to water, ozone, and/or oxygen back to its pre-oxidized
state (e.g., zero valent metal). The optional treatment preferably
occurs without significantly altering the surface properties of the
ALD-formed film layer on the target surface areas. The reducing
step can also increase etch resistance of the ALD-deposited film
layer in known etch processes used in lithography.
[0054] The ALD process can include an annealing step between ALD
cycles and/or after an ALD process to effect a change in the
physical and/or mechanical properties of the ALD-formed film layer
(e.g., densifying the ALD film layer and/or increasing
crystallinity). The ALD-formed layer can be annealed at the same
temperature of the ALD deposition or a different temperature. The
annealing step, if performed, can be conducted at a temperature of
0.degree. C. to 500.degree. C., more specifically 100.degree. C. to
500.degree. C., and even more specifically 200.degree. C. to
400.degree. C. by heating the ALD treated substrate under an inert
atmosphere (i.e., argon, nitrogen). In an embodiment, the annealing
step is performed at a temperature above 100.degree. C.
[0055] Herein, an ALD process comprises one or more ALD cycles
(i.e., one ALD cycle equals two ALD half-cycles) plus any optional
treatments performed between ALD cycles. When film formation is
favored, an ALD cycle can selectively generate a monolayer of
ALD-formed film on a target surface without forming a film on a
non-target surface of a substrate. An ALD process can comprise 1 to
100,000 ALD cycles, 1 to 10,000 ALD cycles, 1 to 1000 ALD cycles,
or 1 to 100 ALD cycles.
[0056] A given ALD cycle can produce a monolayer of ALD-formed
material (target composition) having a thickness of about 0.04 nm
to about 0.10 nm. An ALD-formed film can comprise one or more
monolayers of ALD-formed material. An ALD process can produce an
ALD-formed film having a thickness of about 0.001 nm to about 1000
nm. A 40 cycle ALD process produces a film having a thickness of
about 2.4 nm.
Method 1
[0057] This method is a more specific method of selectively forming
an alumina film on a silicon dioxide surface in the presence of a
metal-containing surface. Area-selectivity occurs at a temperature
between 0.degree. C. and 100.degree. C., which is not observed when
the ALD process is performed at a typical temperature of about
200.degree. C. or higher.
[0058] To illustrate, in the first half-cycle of an ALD process to
form an area-selective alumina film on a silicon oxide surface, a
volatile organoaluminum compound (e.g., trimethyl aluminum,
triethyl aluminum), a precursor of alumina, is delivered by an ALD
apparatus to a chamber containing a substrate. The precursor makes
contact with the exposed surfaces of the substrate and selectively
adsorbs to the silicon oxide surface regions forming an initial
monolayer comprising adsorbed organoaluminum species. In a second
half-cycle of the ALD process, water vapor, ozone, and/or oxygen
are delivered by ALD to the substrate, converting the initial
monolayer to alumina and releasing volatile side products (e.g.,
methane, methanol). Herein, the term "water" means H.sub.2O,
D.sub.2O, or a combination thereof. Other proton donors can be used
for converting the initial monolayer to alumina such as, for
example alcohols (e.g., methanol, ethanol) and carboxylic acids
(e.g., acetic acid).
[0059] Under these conditions, the alumina precursor in the first
half-cycle selectively adsorbs to the silicon oxide surfaces in the
presence of a metal-containing surface. The metal-containing
surface preferably comprises copper, chromium, or cobalt, and
area-selectivity is observed for at least 1 ALD cycle.
[0060] FIG. 1 illustrates the disclosed method using
cross-sectional layer diagrams for a substrate comprising silicon
oxide and copper-containing surfaces. The method comprises
selecting a substrate 10 composed of target surface regions 14
containing silicon oxide (referred to herein as "silicon surfaces")
and non-target surface regions 12 containing copper and/or copper
oxides (referred to herein as "copper surfaces"). The substrate 10
is initially flushed with an inert gas (e.g., argon, nitrogen) at a
selected ALD temperature between 0.degree. C. and 100.degree. C.,
more specifically between 50.degree. C. and 100.degree. C., even
more specifically between 60.degree. C. and 90.degree. C., and most
specifically 75.degree. C. to 85.degree. C. for a period of 1
second to 10 minutes, more preferably 1 minute to 10 minutes, and
most preferably 1 minute to 5 minutes. In a preferred embodiment,
each ALD half-cycle is performed at the same ALD temperature. In
the first ALD half-cycle the substrate is dosed (brought into
contact) with an organoaluminum compound (e.g., trimethyl aluminum
(TMA), triethylaluminum (TEA), referred to herein as alumina
precursor) that deposits substantially or wholly on the silicon
surfaces of the substrate, thereby forming an initial monolayer.
The time of treatment of the alumina precursor with the substrate
can be for a period of 1 second to 10 minutes, more preferably 1
minute to 10 minutes, and most preferably 1 minute to 5 minutes.
The pressure of the alumina precursor can be 10.sup.-1 torr to
10.sup.-5 torr, preferably about 10.sup.-2 torr to 10.sup.-4 torr,
most preferably about 10.sup.-3 torr.
[0061] In this instance, the initial monolayer comprises
organoaluminum species that are covalently linked to one or two
oxygens of the silicon surfaces (e.g., Me.sub.2Al(O--*),
MeAl(O--*).sub.2). The adsorption of precursor to the target
surface can be by covalent or non-covalent binding. After formation
of the initial monolayer, unbound organoaluminum precursor is
purged from the ALD chamber using an inert gas (e.g., argon,
nitrogen) optionally assisted by vacuum. This completes the first
half-cycle. In the second half-cycle, the substrate containing the
initial monolayer is treated with at least one second reactant
(e.g., water vapor, oxygen, ozone, combinations the foregoing). The
second reactant reacts with the adsorbed precursor, thereby forming
layered structure 20 comprising an alumina monolayer film 22
disposed substantially or exclusively on first surface regions 14
(silicon surfaces). The time of treatment with the second reactant
can be for a period of 1 second to 10 minutes, more preferably 1
minute to 10 minutes, and most preferably 1 minute to 5 minutes.
The pressure of the second reactant can be 10.sup.-1 torr to
10.sup.-5 torr, preferably about 10.sup.-2 torr to 10.sup.-4 torr,
most preferably about 10.sup.-3 torr. Another purge using an inert
gas removes unreacted second reactant. In an embodiment, the second
reactant is deionized water vapor. This completes the second
half-cycle of an ALD cycle. In subsequent ALD cycles an alumina
monolayer can be formed substantially or wholly on the alumina
monolayer formed in the previous ALD cycle.
[0062] At the low ALD temperature, copper surfaces remain free of,
or substantially free of, alumina for up to about 40 ALD cycles,
chromium for up to about 3-5 ALD cycles, and cobalt up to about
10-15 ALD cycles. The growth rate of alumina on the silicon
surfaces under these conditions is approximately 0.06 nm/cycle,
indicating that the film grown on the silicon surface after 40 ALD
cycles is about 2.4 nm in thickness.
[0063] The method is performed without using a blocking layer to
protect the metal surfaces during the ALD cycles. In an embodiment,
the method excludes a blocking layer on the copper surfaces. The
copper surfaces have contact with each reactant of each ALD
half-cycle.
[0064] The substrate can be maintained at a constant temperature
for the entire ALD process. Alternatively, the temperature of the
ALD chamber can be adjusted during the purging to assist in removal
of excess reactants (alumina precursor, water vapor, oxygen).
[0065] Non-limiting uses of the layered structure formed by the
above method include etch masks for lithographic processes and
components of a semiconductor devices.
Method 2
[0066] This method applies to any desired target composition of the
ALD film layer (e.g., Al.sub.2O.sub.3) and is illustrated in the
flow diagram of FIG. 2.
[0067] The method utilizes a database of ALD film-forming reactions
(FIG. 2, box 30). A given record of the database includes ALD
reactants, substrate materials, ALD device, ALD conditions,
post-ALD analyses of substrate surfaces. The database can contain
one or more data tables of ALD reactions, each data table
comprising at least one record of an ALD film-forming reaction.
Each record can include metadata associated with a given ALD
reaction (e.g., date, time, origin of reactants, origin of
substrate, treatment of the substrate prior to ALD, criteria for an
acceptable monolayer, and the like). Criteria for an acceptable
monolayer can be based, for example, on elemental analysis of the
top surface, 3-dimensional characterization of the layer by atomic
force microscopy, images of the layer obtained by scanning electron
microscopy, and/or physical properties of the monolayer (e.g.,
thermal and electrical conductivity, resistivity, reflectivity, and
the like).
[0068] The database includes successes and failures of ALD
film-forming reactions. A success can mean an acceptable ALD
monolayer of the target composition was formed by an ALD process on
a given substrate material using a given set of reactants and a
given set of ALD conditions. A success can also mean the elemental
composition of the given substrate surface was changed an
acceptable amount by an ALD process using the given set of
reactants, the given substrate material, and the given set of ALD
conditions. A failure can mean none of, or substantially none of,
an ALD film layer of the target composition was formed on a given
substrate material in an ALD process using a given set of reactants
and a given set of ALD conditions. A failure can also mean the
baseline elemental composition of the surface of the given
substrate material remained unchanged, or substantially unchanged
after an ALD process using the given set of reactants and the given
set of ALD conditions.
[0069] Each record of the database preferably contains information
pertinent to the results of one ALD process. Each record of the
database includes the number of ALD cycles, the pre-ALD and
post-ALD analyses of the surface materials of the substrate before
the ALD process and a measure of the degree to which any change
occurred in the surface composition of the substrate after the ALD
process (e.g., percent change in oxygen content, percent change in
a particular metal content).
[0070] Non-limiting ALD conditions include: substrate temperature
during deposition of first reactant(s), first reactant(s) pressure,
first reactant(s) flow rate, first reactant(s) deposition time,
purge time of first reactant(s), purge gas of first reactant(s),
purge temperature of first reactant(s), substrate temperature
during deposition of second reactant(s), second reactant(s)
pressure, second reactant(s) flow rate, second reactant(s)
deposition time, purge time of second reactant(s), purge gas of
second reactant(s), purge temperature of second reactant(s),
optional annealing temperature, and optional annealing time.
[0071] Each record can also include properties of the ALD-formed
film layer pertinent to its intended use (e.g., thermal and
electrical conductivity, light absorption/transmittance/reflectance
properties, magnetic properties, gas permeation properties,
antimicrobial properties).
[0072] The ALD reaction data can be gathered by submitting
different substrate materials in the form of coupons to a given ALD
process, analyzing the changes to the surface of each coupon after
1 or more ALD cycles, and posting the results for each coupon as a
separate record of the database. A given coupon can contain more
than one substrate material arranged in a manner that allows for
separate analyses of the different surfaces in a given ALD process,
which can be posted as separate records in the database. In this
manner, the database can be constructed to have hundreds,
thousands, hundreds of thousands, even millions of ALD film-forming
reactions using different reactants, substrate materials, and ALD
conditions, including number of ALD cycles.
[0073] A computer-driven or manual search of the database can then
be performed to identify ALD conditions favoring ALD film formation
of a target composition (e.g., alumina) on a target surface of a
substrate while disfavoring film formation on other non-target
surface region(s)) of the substrate, without using an inhibiting
layer or an activating layer to guide the deposition of ALD
reactants.
[0074] In practice, this method comprises (FIG. 2, box 32): i)
selecting a target composition (e.g., alumina) to be formed by an
ALD process, ii) selecting a target material (e.g., silicon oxide)
on which to deposit the target composition by ALD, and iii)
selecting one or more non-target materials (e.g., copper) on which
no ALD film formation is desired. These selected parameters become
input for a search of the ALD reaction database to identify ALD
reactants and ALD conditions favoring ALD film formation of the
target composition on the target material and disfavoring ALD film
formation on the non-target material (FIG. 2, box 34). As a
non-limiting example, the search can identify a first reactant and
a second reactant for forming an alumina film by ALD. The search
can identify ALD conditions including but not limited to a range of
temperatures, times of reactions, and number of ALD cycles for
which alumina film formation using the identified reactants is
favored on silicon oxide but not on copper metal.
[0075] If the search is not successful, additional ALD reactions
can be conducted and entered into the database to fill gaps in the
experimental conditions and results.
[0076] If the search is successful, the method further comprises
(FIG. 2, 36) determining whether common ALD conditions exist within
the reactions found that favor selective ALD deposition of the
target composition on the target material and disfavor deposition
of the target composition on the non-target material.
[0077] If common ALD conditions are obtained, then the ALD is
performed using the identified first reactant, the identified
second reactant, and the identified common ALD conditions with a
substrate comprising surface areas containing the selected target
material and other surface areas containing the non-target
material, (FIG. 2, 38). The result is an ALD film comprising the
ALD target composition selectively disposed on the target material
of the substrate while leaving the non-target material(s) free of,
or substantially free of, any ALD film disposed thereon.
[0078] The search can be restricted to a pre-defined first reactant
and pre-defined second reactant of the ALD process for making the
target composition. In this instance, the search output (e.g., ALD
conditions) will be limited to those associated with the
pre-defined reactants. Otherwise, the search output can include one
or more potential first reactants and one or more potential second
reactants along with their associated ALD conditions favoring
deposition on the target surface and disfavoring deposition on the
non-target surface.
Substrates
[0079] The substrate can be a layered structure comprising one or
more layers having a top surface. The substrate comprises target
surface regions and non-target surface regions composed of
different materials. The substrate, and more particularly the
surface of the substrate, can comprise inorganic or organic
materials such as metals, carbon, and/or polymers. More
particularly, the substrate can comprise a semiconducting material
including, for example, Si, SiGe, SiGeC, SiC, Ge alloys, GaAs,
InAs, InP, silicon nitride, titanium nitride, hafnium oxide, as
well as other III-V or II-VI compound semiconductors. The substrate
can comprise a dielectric material such as, for example, SiO.sub.2,
TiO.sub.2, Al.sub.2O.sub.3, Ta.sub.2O.sub.5 and polymers (e.g.,
polyimides, polamides, polyethylenes). The substrate can also
comprise a layered semiconductor such as Si/SiGe, or a
semiconductor-on-insulator (SOI). In particular, the substrate can
contain a Si-containing semiconductor material (i.e., a
semiconductor material that includes Si). The semiconductor
material can be doped, non-doped or contain both doped and
non-doped regions therein.
[0080] The substrate can have an anti-reflection control layer (ARC
layer) or a bottom ARC layer (BARC layer) to reduce reflectivity of
the film stack. Many suitable BARCs are known in the literature
including single layer BARCs, dual layer BARCs, graded BARCs, and
developable BARCs (DBARCs). The substrate can also comprise a hard
mask, a transfer layer (e.g., planarizing layer, spin-on-glass
layer, spin-on carbon layer), and other materials as required for
the layered device.
[0081] The substrate can be an inflexible structure (e.g., silicon
wafer) or a flexible structure (e.g., polyethylene sheet). The
substrate can be 1-dimensional (e.g., wire), 2-dimensional (e.g., a
wafer), or 3-dimensional (e.g., a bottle).
Utility
[0082] Non-limiting applications of the disclosed methods include
the fabrication of photovoltaic devices, integrated circuit (IC)
chips, MEMS (Microelectromechanical systems) devices, FETs,
displays, and storage devices. More specific layer applications
include capping layers, gate dielectrics, spacers, liners, Cu caps,
etch stops, hard masks, interlevel dielectrics (ILD), permanent
layers, disposable layers for wet and reactive ion etching (RIE)
selectivity, stop layers for chemical mechanical polishing (CMP),
barrier layers, and through silicon via liner layers. Non-limiting
end products for IC chips include toys, energy collectors, solar
devices, and other applications including computer products or
devices having a display, a keyboard or other input device, and a
central processor. Photovoltaic devices can be particularly useful
for solar cells, panels or modules employed to provide power to
electronic devices, homes, buildings, vehicles, etc.
Computer Hardware and Software
[0083] The computer system for implementing the present invention
can take the form of an entirely hardware embodiment, an entirely
software embodiment (including firmware, resident software,
microcode, etc.), or a combination of software and hardware that
may all generally be referred to herein as a "circuit," "module,"
or "system."
[0084] The present invention may be a system, a method, and/or a
computer program product at any possible technical detail level of
integration. The computer program product may include a computer
readable storage medium (or media) having computer readable program
instructions thereon for causing a processor to carry out aspects
of the present invention.
[0085] The computer readable storage medium can be a tangible
device that can retain and store instructions for use by an
instruction execution device. The computer readable storage medium
may be, for example, but is not limited to, an electronic storage
device, a magnetic storage device, an optical storage device, an
electromagnetic storage device, a semiconductor storage device, or
any suitable combination of the foregoing. A non-exhaustive list of
more specific examples of the computer readable storage medium
includes the following: a portable computer diskette, a hard disk,
a random access memory (RAM), a read-only memory (ROM), an erasable
programmable read-only memory (EPROM or Flash memory), a static
random access memory (SRAM), a portable compact disc read-only
memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a
floppy disk, a mechanically encoded device such as punch-cards or
raised structures in a groove having instructions recorded thereon,
and any suitable combination of the foregoing. A computer readable
storage medium, as used herein, is not to be construed as being
transitory signals per se, such as radio waves or other freely
propagating electromagnetic waves, electromagnetic waves
propagating through a waveguide or other transmission media (e.g.,
light pulses passing through a fiber-optic cable), or electrical
signals transmitted through a wire.
[0086] Computer readable program instructions described herein can
be downloaded to respective computing/processing devices from a
computer readable storage medium or to an external computer or
external storage device via a network, for example, the Internet, a
local area network, a wide area network and/or a wireless network.
The network may comprise copper transmission cables, optical
transmission fibers, wireless transmission, routers, firewalls,
switches, gateway computers and/or edge servers. A network adapter
card or network interface in each computing/processing device
receives computer readable program instructions from the network
and forwards the computer readable program instructions for storage
in a computer readable storage medium within the respective
computing/processing device.
[0087] Computer readable program instructions for carrying out
operations of the present invention may be assembler instructions,
instruction-set-architecture (ISA) instructions, machine
instructions, machine dependent instructions, microcode, firmware
instructions, state-setting data, configuration data for integrated
circuitry, or either source code or object code written in any
combination of one or more programming languages, including an
object oriented programming language such as Smalltalk, C++, or the
like, and procedural programming languages, such as the "C"
programming language or similar programming languages. The computer
readable program instructions may execute entirely on the user's
computer, partly on the user's computer, as a stand-alone software
package, partly on the user's computer and partly on a remote
computer or entirely on the remote computer or server. In the
latter scenario, the remote computer may be connected to the user's
computer through any type of network, including a local area
network (LAN) or a wide area network (WAN), or the connection may
be made to an external computer (for example, through the Internet
using an Internet Service Provider). In some embodiments,
electronic circuitry including, for example, programmable logic
circuitry, field-programmable gate arrays (FPGA), or programmable
logic arrays (PLA) may execute the computer readable program
instructions by utilizing state information of the computer
readable program instructions to personalize the electronic
circuitry, in order to perform aspects of the present
invention.
[0088] Aspects of the present invention are described herein with
reference to flowchart illustrations and/or block diagrams of
methods, apparatus (systems), and computer program products
according to embodiments of the invention. It will be understood
that each block of the flowchart illustrations and/or block
diagrams, and combinations of blocks in the flowchart illustrations
and/or block diagrams, can be implemented by computer readable
program instructions.
[0089] These computer readable program instructions may be provided
to a processor of a general purpose computer, special purpose
computer, or other programmable data processing apparatus to
produce a machine, such that the instructions, which execute via
the processor of the computer or other programmable data processing
apparatus, create means for implementing the functions/acts
specified in the flowchart and/or block diagram block or blocks.
These computer readable program instructions may also be stored in
a computer readable storage medium that can direct a computer, a
programmable data processing apparatus, and/or other devices to
function in a particular manner, such that the computer readable
storage medium having instructions stored therein comprises an
article of manufacture including instructions which implement
aspects of the function/act specified in the flowchart and/or block
diagram block or blocks.
[0090] The computer readable program instructions may also be
loaded onto a computer, other programmable data processing
apparatus, or other device to cause a series of operational steps
to be performed on the computer, other programmable apparatus or
other device to produce a computer implemented process, such that
the instructions which execute on the computer, other programmable
apparatus, or other device implement the functions/acts specified
in the flowchart and/or block diagram block or blocks.
[0091] The flowchart and block diagrams in the Figures illustrate
the architecture, functionality, and operation of possible
implementations of systems, methods, and computer program products
according to various embodiments of the present invention. In this
regard, each block in the flowchart or block diagrams may represent
a module, segment, or portion of instructions, which comprises one
or more executable instructions for implementing the specified
logical function(s). In some alternative implementations, the
functions noted in the blocks may occur out of the order noted in
the Figures. For example, two blocks shown in succession may, in
fact, be executed substantially concurrently, or the blocks may
sometimes be executed in the reverse order, depending upon the
functionality involved. It will also be noted that each block of
the block diagrams and/or flowchart illustration, and combinations
of blocks in the block diagrams and/or flowchart illustration, can
be implemented by special purpose hardware-based systems that
perform the specified functions or acts or carry out combinations
of special purpose hardware and computer instructions.
[0092] FIG. 3 shows a structure of a computer system and computer
program code that may be used to implement a method of processing,
including natural-language processing, to enter, search, retrieve,
and report information contained in an ADL reaction database and
perform other processes disclosed herein. In FIG. 3, computer
system 101 comprises a processor 103 coupled through one or more
I/O Interfaces 109 to one or more hardware data storage devices 111
and one or more I/O devices 113 and 115. Hardware data storage
devices 111 can contain, for example, the ADL reaction
database.
[0093] Hardware data storage devices 111 may include, but are not
limited to, magnetic tape drives, fixed or removable hard disks,
optical discs, storage-equipped mobile devices, and solid-state
random-access or read-only storage devices. I/O devices may
comprise, but are not limited to: input devices 113, such as
keyboards, scanners, handheld telecommunications devices,
touch-sensitive displays, tablets, biometric readers, joysticks,
trackballs, or computer mice; and output devices 115, which may
comprise, but are not limited to printers, plotters, tablets,
mobile telephones, displays, or sound-producing devices. Data
storage devices 111, input devices 113, and output devices 115 may
be located either locally or at remote sites from which they are
connected to I/O Interface 109 through a network interface.
[0094] Processor 103 may also be connected to one or more memory
devices 105, which may include, but are not limited to, Dynamic RAM
(DRAM), Static RAM (SRAM), Programmable Read-Only Memory (PROM),
Field-Programmable Gate Arrays (FPGA), Secure Digital memory cards,
SIM cards, or other types of memory devices.
[0095] At least one memory device 105 contains stored computer
program code 107, which is a computer program that comprises
computer-executable instructions. The stored computer program code
can include a program for natural-language processing that
implements the disclosed methods. The data storage devices 111 may
store the computer program code 107. Computer program code 107
stored in the storage devices 111 can be configured to be executed
by processor 103 via the memory devices 105. Processor 103 can
execute the stored computer program code 107.
[0096] Thus the present invention discloses a process for
supporting computer infrastructure, integrating, hosting,
maintaining, and deploying computer-readable code into the computer
system 101, wherein the code in combination with the computer
system 101 is capable of performing the disclosed methods.
[0097] Any of the components of the present invention could be
created, integrated, hosted, maintained, deployed, managed,
serviced, supported, etc. by a service provider. Thus, the present
invention discloses a process for deploying or integrating
computing infrastructure, comprising integrating computer-readable
code into the computer system 101, wherein the code in combination
with the computer system 101 is capable of performing the disclosed
methods.
[0098] One or more data storage units 111 (or one or more
additional memory devices not shown in FIG. 3) may be used as a
computer-readable hardware storage device having a
computer-readable program embodied therein and/or having other data
stored therein, wherein the computer-readable program comprises
stored computer program code 107. Generally, a computer program
product (or, alternatively, an article of manufacture) of computer
system 101 may comprise said computer-readable hardware storage
device.
[0099] While it is understood that program code 107 may be deployed
by manually loading the program code 107 directly into client,
server, and proxy computers (not shown) by loading the program code
107 into a computer-readable storage medium (e.g., computer data
storage device 111), program code 107 may also be automatically or
semi-automatically deployed into computer system 101 by sending
program code 107 to a central server (e.g., computer system 101) or
to a group of central servers. Program code 107 may then be
downloaded into client computers (not shown) that will execute
program code 107.
[0100] Alternatively, program code 107 may be sent directly to the
client computer via e-mail. Program code 107 may then either be
detached to a directory on the client computer or loaded into a
directory on the client computer by an e-mail option that selects a
program that detaches program code 107 into the directory.
[0101] Another alternative is to send program code 107 directly to
a directory on the client computer hard drive. If proxy servers are
configured, the process selects the proxy server code, determines
on which computers to place the proxy servers' code, transmits the
proxy server code, and then installs the proxy server code on the
proxy computer. Program code 107 is then transmitted to the proxy
server and stored on the proxy server.
[0102] In one embodiment, program code 107 is integrated into a
client, server and network environment by providing for program
code 107 to coexist with software applications (not shown),
operating systems (not shown) and network operating systems
software (not shown) and then installing program code 107 on the
clients and servers in the environment where program code 107 will
function.
[0103] The first step of the aforementioned integration of code
included in program code 107 is to identify any software including
the network operating system (not shown), which is required by
program code 107 or that works in conjunction with program code 107
and is on the clients and servers where program code 107 will be
deployed. This identified software includes the network operating
system, where the network operating system comprises software that
enhances a basic operating system by adding networking features.
Next, the software applications and version numbers are identified
and compared to a list of software applications and correct version
numbers that have been tested to work with program code 107. A
software application that is missing or that does not match a
correct version number is upgraded to the correct version.
[0104] A program instruction that passes parameters from program
code 107 to a software application is checked to ensure that the
instruction's parameter list matches a parameter list required by
the program code 107. Conversely, a parameter passed by the
software application to program code 107 is checked to ensure that
the parameter matches a parameter required by program code 107. The
client and server operating systems, including the network
operating systems, are identified and compared to a list of
operating systems, version numbers, and network software programs
that have been tested to work with program code 107. An operating
system, version number, or network software program that does not
match an entry of the list of tested operating systems and version
numbers is upgraded to the listed level on the client computers and
upgraded to the listed level on the server computers.
[0105] After ensuring that the software, where program code 107 is
to be deployed, is at a correct version level that has been tested
to work with program code 107, the integration is completed by
installing program code 107 on the clients and servers.
[0106] Embodiments of the present invention may be implemented as a
method performed by a processor of a computer system, as a computer
program product, as a computer system, or as a processor-performed
process or service for supporting computer infrastructure.
[0107] The following examples illustrate forming alumina on silicon
oxide selectively in the presence of a copper layer, chromium
layer, and cobalt layer using an ALD temperature of 80.degree.
C.
EXAMPLES
Preparation of Substrates
[0108] A 50 nm thick copper metal film was evaporated onto a four
inch reclaimed silicon wafer using a circular shadow mask that
protected a portion of the native SiO.sub.2 surface from Cu
deposition. The portion of the wafer on which the copper film was
deposited had a chromium adhesion layer disposed on the silicon
substrate. The native SiO.sub.2 surface had a thickness of about 2
nm. The copper film was deposited at a pressure of 10.sup.-5 torr
and had a surface native oxide content of about 17% (see FIG. 4 at
0 cycles). No treatments prior to ALD were performed on the wafers
after thermal deposition of the copper.
ALD Process
[0109] The following general procedure was used to treat sample
substrates by ALD to form alumina films disposed on the substrate
surface. Wafers containing both SiO.sub.2 and Cu surfaces were
broken up into coupons. A portion of the coupons contained a SAM on
the Cu surface, another portion of the coupons contained no SAM.
The individual coupons were loaded into an ALD chamber. The
Al.sub.2O.sub.3 deposition was performed using trimethyl aluminum
(TMA) as the organometallic precursor. In a given ALD cycle, the
substrate surface was first saturated with the precursor at
80.degree. C. for 4 minutes at 10.sup.-3 torr. The ALD chamber was
then evacuated to remove unadsorbed TMA. In a second half-cycle, a
3 minute pulse of deionized water at 10.sup.-3 torr was then
introduced to the ALD chamber, thereby hydrolyzing the adsorbed
trimethyl aluminum at the substrate surface and producing an
alumina monolayer having reactive hydroxyl surface groups. This
procedure represents one ALD cycle where the film thickness
obtained after each cycle was approximately 0.06 nm. Coupons were
removed from the ALD chamber after every ten cycles for a total of
70 ALD cycles. Eight coupons per example below represent 0, 10, 20,
30, 40, 50, 60, and 70 ALD cycles, respectively.
Analysis
[0110] The coupons were then characterized by X-ray photoelectron
spectroscopy (XPS) to measure relative content of Al, Si, and O on
the silicon dioxide and Cu surfaces.
Results
[0111] Example 1 (comparison). Example 1 includes 8 sample coupons
having a self-assembled monolayer (SAM) disposed on the Cu surface.
Hexamethyldisilazane (HMDS) was employed to block the Cu surface.
The SAM appeared disordered and contained pin-holes.
[0112] The XPS results for the Cu area are shown in FIG. 4. At 0
ALD cycles the baseline concentrations were: oxygen 17% and copper
7%. The relative concentration of oxygen on the Cu surface remained
constant up to 40 cycles. At 50 cycles and above, a continuous
increase in the surface oxygen concentration was observed on the Cu
surface. The signal from the surface Al on Cu was difficult to
detect as the significant signal overlap between Cu and Al
prevented accurate deconvolution of the peaks.
[0113] The XPS results of the Si area are shown in FIG. 5. The
baseline concentrations of the Si area at 0 ALD cycles were: oxygen
43%, silicon 29%, and aluminum 2%. The oxygen and aluminum
concentrations increased immediately on the silicon surface
consistent with the growth of an Al.sub.2O.sub.3 film. In ALD
cycles 1-40, the aluminum signal steadily rose while the silicon
signal steadily declined.
[0114] Example 2. The second set of 8 coupons contained no SAM on
the copper surface. The XPS results for the Cu area are shown in
FIG. 6. The baseline concentration of oxygen of the Cu surface at 0
ALD cycles was approximately 18%. This concentration remained
relatively constant up to 40 ALD cycles. These results indicate the
native properties of the Cu surface are responsible for inhibiting
growth of Al.sub.2O.sub.3 on the Cu surface under these
conditions.
[0115] Example 3. A third set of 8 coupons used a substrate
containing silicon dioxide and chromium surface regions. The ALD
was performed as in Example 2 without a SAM. The XPS analysis of
the aluminum content on the chromium and silicon dioxide surface
regions as a function of number of ALD cycles is shown in FIG. 7.
The baseline concentration of oxygen of the chromium surface at 0
ALD cycles was approximately 0%. At 10 ALD cycles, the aluminum
content was 18% and 4% on the silicon dioxide and chromium
surfaces, respectively. These results indicate that selective
growth of Al.sub.2O.sub.3 on the silicon dioxide surface can be
maintained for about 1-3 ALD cycles in the presence of chromium
under these conditions.
[0116] Example 4. A fourth set of 8 coupons used a substrate
containing silicon dioxide and cobalt surface regions. The ALD was
performed as in Example 2 without a SAM. The XPS analysis of the
aluminum content on the cobalt and silicon dioxide surface regions
as a function of number of ALD cycles is shown in FIG. 8. The
baseline concentration of oxygen of the chromium surface at 0 ALD
cycles was approximately 0%. At 10 ALD cycles, the aluminum content
was 15% and 0% on the silicon dioxide and cobalt surfaces,
respectively. At 20 ALD cycles, the aluminum content was 20% and 4%
on the silicon dioxide and cobalt surfaces, respectively. These
results indicate that selective growth of Al.sub.2O.sub.3 on the
silicon dioxide surface can be maintained for about 10-15 ALD
cycles in the presence of chromium under these conditions.
[0117] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
When a range is used to express a possible value using two
numerical limits X and Y (e.g., a concentration of X ppm to Y ppm),
unless otherwise stated the value can be X, Y, or any number
between X and Y.
[0118] The description of the present invention has been presented
for purposes of illustration and description, but is not intended
to be exhaustive or limited to the invention in the form disclosed.
Many modifications and variations will be apparent to those of
ordinary skill in the art without departing from the scope and
spirit of the invention. The embodiments were chosen and described
in order to best explain the principles of the invention and their
practical application, and to enable others of ordinary skill in
the art to understand the invention.
* * * * *